BACKGROUND AND OBJECTIVE: To investigate the effect of patient sex on presentation and outcomes of branch retinal vein occlusion (BRVO). PATIENTS AND METHODS: Retrospective chart review cohort study of 188 eyes with BRVO and cystoid macular edema (CME); 81 treatment-naïve eyes were selected for subgroup analysis. RESULTS: Males had better visual acuity (VA) in the BRVO eye at baseline compared to females (log-MAR: 0.49 ± 0.47 vs. 0.62 ± 0.53; P = .04); this was not present at the final visit (males: 0.41 ± 0.40 vs. females: 0.59 ± 0.60; P = .10). In treatment-naïve eyes, both sexes had similar VA at baseline (males: 0.42 ± 0.29 vs. females: 0.59 ± 0.46; P = .09); however, at the final visit, males had better VA compared to females (0.38 ± 0.43 vs. 0.66 ± 0.67; P = .03). On average, males received more anti-VEGF injections when adjusting for follow-up (P = .04). CONCLUSIONS: Significant sex differences in VA and treatment of eyes with BRVO and CME were noted. Further investigation is needed to understand sex differences in eyes with BRVO and CME. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:564-572.].